Re: Passing a GUI handle to a socket and Postmessage back to GUI

"Tom Serface" <>
Fri, 13 Mar 2009 21:47:55 -0700
Ah, I see now that you are deleting the pointer in the message handler.
Sorry, it's just a common mistake (the scope) thing so I thought I'd mention
it, but what you're doing looks OK to me.


"KW" <> wrote in message

Could it go out of scope even if I use:

CString * ptrToData = new CString(buffer) ;

and passed the pointer to the message handler??

I was under the impression that this would stay on the heap until I
deleted it. And, in this case, the "new" CString is deleted in the message
handler function. If it can still go out of scope in this situation, I
would need to create a global variable/array to hold the messages.

Do I need to be concerned about it going out of scope and what would you


"Tom Serface" <> wrote in message

I would probably use a function to set the msg window, but this would work
OK. Since you are using PostMessage you may have trouble with the data
since it may go out of scope before it's actually used. You may want to
use SendMessage instead.

You will also want to make sure the window is a valid window before
posting to it.


"Discovery" <> wrote in message

"KW" <>

I have a MDI application with several child windows and a TCPIP server.
I want to pass the handle (of one child) to a server socket class so it
can post a message to the child window when data is received. When the
data is received by the child window, a listbox will display the data.

I have it working, but I wonder if there is a better way of passing (or
getting) the handle. I have to pass it twice to get it into the
OnReceive() Handler of CServer.cpp.

// Click a button and start the listener - couldn't get it to work in
constructor (handle not created yet?) - "SocketWindow" is UI class
void SocketWindow::OnButton1()
   sockServ = new MySocket(CWnd::m_hWnd); //Is this the best way to
get/pass the handle?

void SocketWindow::OnSockMSG(UINT wParam, long lParam)
   CString * ptr = (CString *)wParam;



// These 4 lines are from MySocket.h
virtual ~MySocket();
CServer client;
HWND ChildWindowHandle;

// Constructor MySocket.cpp
MySocket::MySocket(HWND MyHandle)
    ChildWindowHandle = MyHandle;

// MySocket.cpp
void MySocket::OnAccept(int nErrorCode)
    if (nErrorCode == 0)

           // IS THIS A PROBLEM? "client" is declared in CServer.h
           client.HandleToChld = ChildWindowHandle ;

// CServer.cpp
void CServer::OnReceive(int nErrorCode)
    char buffer[1024] ;
    memset(buffer, 0, sizeof(buffer)) ;
    this->Receive(buffer, sizeof(buffer)) ;

    CString result(buffer);

    CString * ptrToData = new CString(result) ;

    // "WM_SCKTMSG_RECV" is defined in stdAfx.h (#define
WM_SCKTMSG_RECV WM_USER + 3), executes "OnSockMSG" above

    ::PostMessage(HandleToChld, WM_SCKTMSG_RECV, (WPARAM)ptrToData,


Although this code currently works, it does not feel right (passing the
handle in the constructor??).
There has to be a better way of doing this. Any suggestions?


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